Message of the Markets

Declines reflect slowing global growth more than U.S. taxes, as the charts show.

To a man with a hammer, every problem looks like a nail. And to some supply-siders, every market move reflects the effect of taxes.

An op-ed piece in Tuesday's Wall Street Journal attributes the current stock-market swoon to the hikes in capital-gains taxes that took effect in 2013. Those changes boosted the long-term cap-gains rate on the upper-income earners by more than half, to 23.8% from 15%, while short-term gains would be taxed...